The invention relates to a device for collecting sheets, such device having a receiving tray to which the sheets that are moved in a direction of transport along an at least approximately horizontal portion of an imaginary trajectory can be fed individually, and a movably mounted bottom portion of the receiving tray. The bottom portion of the tray, having an adjusting element for adjusting the position, is upwardly inclined toward the horizontal in the direction of transport and intersects the imaginary trajectory.
Trays for collecting sheets transported along a path are generally well known, see e.g. U.S. Pat. No. 4,350,333, issued Sept. 21, 1982, in the name of Landa. Such patent discloses a device in the form of a stacking means for copy sheets, in particular copy sheets fed by a copier. Typical copiers or printing systems operate at a relatively high speed, i.e., the sheets are fed at a relatively high frequency rate, which automatically leads to a correspondingly high speed at which the sheets are transported to the collection tray. Due to the high speed at which the sheets move along the trajectory before reaching the collection tray, the collecting process itself is inaccurate. This is because the support surface of the tray is upwardly inclined in the direction of transport in order to slow the sheets down. The individual sheets are deposited on top of each other with a degree of lateral offset. In high speed copiers or printing systems, the formation of stacks whose sheets are in alignment is of utmost importance. This is particularly the case if the device concerned has a collection tray shiftable in the horizontal plane transversely to the direction of transport, and if the stacks which consist of aligned sets of sheets are to be deposited on top of each other with a predetermined specified lateral displacement.
In the aforementioned patent, the individual sheets are prevented from being laterally displaced by the adjusting element for the bottom portion of the collection tray being controlled by an electric sensing and driving device. Accordingly, irrespectively of how thick the stack of sheets is which rests on the bottom portion, the sheets always drop from substantially the same height. The electric sensing and driving device renders the apparatus much more complicated and, thus, results in an increase in production costs.